In general, an antenna for vehicles to receive or transmit radio waves is installed at the inside or outside of a vehicle. FIG. 1 illustrates one exemplary antenna installed at the outside of a vehicle. A roof antenna 60 for vehicles may be combined with a vehicle roof 50. The roof antenna 60 may be referred to as a shark fin antenna due to a design thereof.
The roof antenna 60 is generally configured such that an upper case 65 and a lower case 63 are fastened to each other and an antenna is disposed in the upper case 65 and the lower case 63.
FIGS. 2(a) to 3 are views illustrating a conventional roof antenna. Such a conventional roof antenna will be described with reference to reference numerals shown in FIG. 1.
FIG. 2(a) is a view illustrating the lower case 63 of the roof antenna 60 combined with the surface of the vehicle roof 50. The lower case 63 may be fastened to the vehicle roof 50 through mechanical connection parts 91, 92, 93, 95, 97 and 99 using bolts or nuts. The surface of the lower case 63 combined with the surface of the vehicle roof 50 may include first to fourth diaphragms 71, 73, 75 and 77 as watertight diaphragms (ribs) to prevent the introduction of water.
FIG. 2(b) is a cross-sectional view of the lower case 63. The cross-section of the first diaphragm 71 corresponds to a portion 81 and the cross-section of the second diaphragm 73 corresponds to a portion 83. Since vehicles have different R values (curvatures) of vehicle roof frames (as the R value of a vehicle roof frame increases, flatness of the vehicle roof frame increases), watertight diaphragms having different shapes according to vehicle types are developed. The reason for this is that, when the roof 50 and the lower case 63 are fastened to each other using nuts, diaphragms (ribs) may be pressed.
Further, other conventional problems will be described with reference to FIG. 3. As exemplarily shown in FIG. 3, it may be known from an enlarged view of a connection portion between an upper case 10 (65 of FIG. 1) and a lower case 63 of a roof antenna 60 that a diaphragm 11 of the upper case 10 may be coupled with a rubber member 23 of the lower case 63. If water is sprayed at a high pressure to such a coupling portion, a watertight function may fail. Therefore, development of an improved roof antenna is required.